Options on changing k16's?
04-18-2004, 10:40 PM
#16
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Kevin,
Ummmm... here comes a dumb question. Are the wastegates built *into* the turbo units themselves? I sort of figured they were an external piece of hardware that also needed to have the "Kevin magic touch". So... when you build up a stage 2 GT1 turbo, is the wastegate already modified? Is it an extra process? Any idea how the stage 2 will work with my Gemballa ECU? Am I going to have to have Viperbob work his magic on my ECU as well?
And... 62,500 miles! Why haven't my turbos started leaking yet? I'm gettimg anxious for this upgrade!
Ummmm... here comes a dumb question. Are the wastegates built *into* the turbo units themselves? I sort of figured they were an external piece of hardware that also needed to have the "Kevin magic touch". So... when you build up a stage 2 GT1 turbo, is the wastegate already modified? Is it an extra process? Any idea how the stage 2 will work with my Gemballa ECU? Am I going to have to have Viperbob work his magic on my ECU as well?
And... 62,500 miles! Why haven't my turbos started leaking yet? I'm gettimg anxious for this upgrade!
04-18-2004, 11:19 PM
#17
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Jean;
K24's won't beat the hybrid K16's period.. I'll machine the turbine wheels, change the A/R if I have to, in the end it won't happen. The last dyno that was run did 578 rwhp.. with turbo's that look like those pictured. Fact, the ball-bearing GT25 & 28's have SMALLER turbine wheels than the K16 and many tuner have adapted them. Bottom line is if the customer want or has K24, the same mods can be done.. You just have a 350-400RPM shift due to the A/R and larger turbine wheel. There was a gentleman who posted on Rennlist a few months ago about his Andial 3.8 993TT motor, the GT1's beat the K24's in torque and peaks higher and quicker... I know there are some tuners across the pond that say that you have a restriction in the turbine housings... Prove it to me with a dyno sheet...
Steve;
The wastegate are built into the turbine housings, you can see the hinge on the picture. It is an extra process. The Gemballa ECU is very good and adapts well to GT1's, Stage 2 with a 5bar should be enough. I'd run the ECU and see how the AFR's are before dumping the program. You've done well with hot shut downs and oil changes!
K24's won't beat the hybrid K16's period.. I'll machine the turbine wheels, change the A/R if I have to, in the end it won't happen. The last dyno that was run did 578 rwhp.. with turbo's that look like those pictured. Fact, the ball-bearing GT25 & 28's have SMALLER turbine wheels than the K16 and many tuner have adapted them. Bottom line is if the customer want or has K24, the same mods can be done.. You just have a 350-400RPM shift due to the A/R and larger turbine wheel. There was a gentleman who posted on Rennlist a few months ago about his Andial 3.8 993TT motor, the GT1's beat the K24's in torque and peaks higher and quicker... I know there are some tuners across the pond that say that you have a restriction in the turbine housings... Prove it to me with a dyno sheet...
Steve;
The wastegate are built into the turbine housings, you can see the hinge on the picture. It is an extra process. The Gemballa ECU is very good and adapts well to GT1's, Stage 2 with a 5bar should be enough. I'd run the ECU and see how the AFR's are before dumping the program. You've done well with hot shut downs and oil changes!
04-19-2004, 01:42 AM
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Hey Kevin, those look like a set of turbos I installed last week....
Well my tubos made it for the weekend at Buttonwillow. They are coming off tomorrow and going to Kevin for a little overhaul. And they are K24s that will be getting a larger (stage 4 or a little better) compressor wheel (I am hoping for titanium), ZC, the ceramic coating and the wategate mod...
With the K24s as is, I have no lag time (very low restriction exhaust) so I think these will be just fine.
Well my tubos made it for the weekend at Buttonwillow. They are coming off tomorrow and going to Kevin for a little overhaul. And they are K24s that will be getting a larger (stage 4 or a little better) compressor wheel (I am hoping for titanium), ZC, the ceramic coating and the wategate mod...
With the K24s as is, I have no lag time (very low restriction exhaust) so I think these will be just fine.
04-19-2004, 02:17 AM
#20
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Kevin, you are right, I was on the phone yesterday with a reknown european tuner who is a friend, and he had serious doubts about this type of hybrids (he does not know you) performing better than the typical modified K24. Thank you for your explanations
I guess if Bob is going with K24s, it should work for me as well, targeting the same hp, and hardly any mufflers, no cats and headers in my car.
Steve (CA993Twin), the K24 turbos are finally out, here is a picture that shows the internal WG , or at least what I think it is.
Jean
I guess if Bob is going with K24s, it should work for me as well, targeting the same hp, and hardly any mufflers, no cats and headers in my car.
Steve (CA993Twin), the K24 turbos are finally out, here is a picture that shows the internal WG , or at least what I think it is.
Jean
04-19-2004, 03:46 AM
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Bob;
Those were actually Sharksters turbo's that I did for the shootout. A little lesson for all of us, if you look closely at the compressor housing you will see a raised boss for the turbo ID tag. This is a dead give away for being 996TT turbochargers, the 993's have the ID tags on the backplates. However, the main casting number is the same and every other detail is the same. The turbine housings are vastly different and will not work on the 993TT.
Jean;
Over time I know where the K24 reasoning has come from. In truth when confronted, it is far easier for them to use bolt on readily available parts, than to CNC, and hand machine turbocharger parts like we can in the States.
Those were actually Sharksters turbo's that I did for the shootout. A little lesson for all of us, if you look closely at the compressor housing you will see a raised boss for the turbo ID tag. This is a dead give away for being 996TT turbochargers, the 993's have the ID tags on the backplates. However, the main casting number is the same and every other detail is the same. The turbine housings are vastly different and will not work on the 993TT.
Jean;
Over time I know where the K24 reasoning has come from. In truth when confronted, it is far easier for them to use bolt on readily available parts, than to CNC, and hand machine turbocharger parts like we can in the States.
04-19-2004, 05:10 AM
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Re: Options on changing k16's?
mb97tts
I have been down this path
Here is what I discovered along the way.....
- YES, a turbo change will help. 993TT's run out of air after 5500rpm.
- New turbos will increase the airflow [and therefore power] in the upper rev range.
Dyno chart of a standard 993.
[ Ignore the kw figures, the shape is the important issue.]
Note the power dropping off at 5500rpm
This dyno sheet shows the same car, with ONLY THE TURBOS CHANGED [ to K24's ]
- the power curve is now flat all the way to redline, because the larger turbos have the ability to supply the extra air required.
- look at the gain at 6500rpm !!!
I have been down this path
Here is what I discovered along the way.....
Originally posted by mb97tts
....So, S ecu, have the oil cooler, will a turbo change help?
....So, S ecu, have the oil cooler, will a turbo change help?
- New turbos will increase the airflow [and therefore power] in the upper rev range.
Dyno chart of a standard 993.
[ Ignore the kw figures, the shape is the important issue.]
Note the power dropping off at 5500rpm
This dyno sheet shows the same car, with ONLY THE TURBOS CHANGED [ to K24's ]
- the power curve is now flat all the way to redline, because the larger turbos have the ability to supply the extra air required.
- look at the gain at 6500rpm !!!
Last edited by Q; 04-19-2004 at 05:27 AM.
04-19-2004, 05:17 AM
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Originally posted by mb97tts
... If I were to replace my k16's what would be a good choice?
... If I were to replace my k16's what would be a good choice?
...no lag, and extra air flow up top where it is needed.
- By accident, a set of K24's were hiflowed for me instead - long story, don't ask
- It is my intention to replace these turbos with a set of Kevin's K16's
- My K24's would be fine -without cats - but I wish to retain them.
04-19-2004, 05:18 AM
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Originally posted by mb97tts
....And can I just do that without doing anything to my ecu?
....And can I just do that without doing anything to my ecu?
- The computer still limits the boost to 0.8bar
- The computer compensates for extra air, and the A/F ratios do not lean out. [it actually went slightly richer] - look at the dotted lines
- The car will feel standard, but with a VERY strong top end.
If you do change the computer, the gains are much greater.
This dyno sheet shows:
- New turbos with New Computer
- New turbos with standard computer
- Standard car
My advice ....for what it is worth
- Don't re-invent the [turbo] wheel, just buy a set of Kevins K16's
....the improvement will be substantial and hassle free.
- When the "modification bug" bites again, make your decision on which computer to upgrade to.
Hope this is of help
Cheers
Q
04-19-2004, 06:21 AM
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thanks Dan
Modifiying the 993 was something I had wanted to do for several years.
I made the point of following it from beginning to end - rather than just sending it out.
Even got my hands dirty and changed the turbos myself LOL
NZ951
Another Kiwi !
its an invasion !!
....or just a flock ?
A/F ratio
The 993TT's run [incredibly] rich under boost to keep the heads / valves cool
10.5:1 is standard
.......all you "water pumper" guys have it easy
Modifiying the 993 was something I had wanted to do for several years.
I made the point of following it from beginning to end - rather than just sending it out.
Even got my hands dirty and changed the turbos myself LOL
NZ951
Another Kiwi !
its an invasion !!
....or just a flock ?
A/F ratio
The 993TT's run [incredibly] rich under boost to keep the heads / valves cool
10.5:1 is standard
.......all you "water pumper" guys have it easy
04-19-2004, 06:49 AM
#29
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I took my turbo water pump off! 10.5 still seems rich still, have you guys thought of water injection to cool the valves and run leaner? That would be a better solution. It would be interesting to see the EGT's at 10.5 and 11.5
04-19-2004, 06:58 AM
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You gota get the grease under the nails to really understand how it all works I recon.
http://drt.linuxnet.co.nz - I built this with my brotherinlaw over 7 years. We built everything ourselves.
Its a boxer engine!! so I can post it here right?? (what I used to tell the Porsche club at the fun days too heh)
Interesting your comments on AFR, I might email Mr RUF and ask him what the BTR should be under full boost.
http://drt.linuxnet.co.nz - I built this with my brotherinlaw over 7 years. We built everything ourselves.
Its a boxer engine!! so I can post it here right??
(what I used to tell the Porsche club at the fun days too heh)Interesting your comments on AFR, I might email Mr RUF and ask him what the BTR should be under full boost.